list = input('请输入列表：')
str = input('请输入你要找的字符：')
num = int(input('请输入你要找第几次：'))
print(findstr(list,str,num))

s1 = {10,20,30,40,50,}
s3 = {'abcdefg','silfjl'}
print(s3)
print(s1)
s1 = set()
s2 = {}
print(type(s1))
print(type(s2))

s1 = {10,20}
s1.add(100)
s1.add(10)
print(s1)
s1.update('slfjs')
print(s1)
s1.remove(10)
print(s1)
s1.discard(10)
print(s1.pop())
print(s1)
print('l' in s1)